The present invention relates to electrical energy distribution systems, as well as to the contactors for such systems.
Electrical energy distribution systems are already known which comprise:
at least two distribution circuits, with each of which is associated an electrical power source powering the corresponding distribution circuit through a controllable power contactor;
at least one controllable interconnection contactor, able to interlink said distribution circuits on that side of said power contactors which is away from said power sources; and
a common control device for the set of said contactors.
Thus, in such a system, each distribution circuit is powered by its own source through the corresponding power contactor, but, should a source be defective, said corresponding distribution circuit can be powered by the source of at least one other distribution circuit, through at least one interconnection contactor.
Distribution systems of this type are used in particular on board aircraft. In this case, each distribution circuit generally comprises a conducting distribution bar powering in parallel a plurality of electrical loads and each source consists either of a generator, driven by an engine of the aircraft or by an auxiliary power unit, or consists of batteries, or else of AC/DC or DC/AC transformers.
Such known electrical energy distribution systems have some drawbacks. Specifically, in order to avoid any untimely coupling of the power sources at the moment of the switching of an interconnection contactor, these known systems, which continuously detect the closed or open state of each contactor, are obliged to wait for the confirmation of the opening of the power contactor associated with the defective source before closing the interconnection contactor or contactors. Hence, this results in sequential operation imposing limits on the speed of switching of said contactors. Moreover, such permanent detection of the state of each contactor entails the existence of wire links between said contactors and the control device, thereby increasing the weight and the cost of said systems.
The object of the present invention is to remedy these drawbacks. It relates to a distribution system of the abovementioned type, improved in such a way as to benefit from greater speed of operation and to allow the elimination of the links between the various contactors and the common control device.
Accordingly, according to the invention, the electrical energy distribution system of the type recalled hereinabove is noteworthy in that:
said common control device is a programmable computer opening and closing said power and interconnection contactors, without prior checking of the open or closed state of said contactors, according to a truth table indicating, for each possible combination of the operating states, correct or defective, of said electrical power sources, the open or closed state which each of said power and interconnection contactors must take; and
with each interconnection contactor there is associated a prevention device able to prevent the closure of said interconnection contactor if its contact terminals are simultaneously energized.
Thus, should a power source be defective, the operation of the control device is no longer sequential and the latter can immediately instigate the switchings necessary for powering the circuit linked to the defective source without concerning itself with the state of said contactors. However, safety is complete since no possibility of coupling of power sources exists, owing to the action of said closure prevention devices.
Preferably, also to avoid any possibility of coupling of sources at the moment of cutting a source into circuit, for example after switching a source on or off, there is provision that, with each power contactor, there is also associated a prevention device, able to prevent the closure of said power contactor, if its contact terminals are simultaneously energized.
In the usual case where said common control device is linked to each of said power contactors and interconnection contactor by an opening control line and by a closure control line, said prevention device associated with such a contactor is interposed in said closure control line of this contactor. Such a prevention device can comprise:
two voltage detectors, respectively linked to said terminals of the corresponding contactor; and
a logic device, linked to said closure control line and to said voltage detectors and preventing the closure of the corresponding contactor if its contact terminals are simultaneously energized.
Although the prevention device can form an add-on unit to a contactor of known type, it is often preferable for said prevention device and said contactor to form a single constructional unit.
The present invention therefore relates, moreover, to an electrical contactor of the type comprising:
two contact terminals and a moveable member, which can occupy, with respect to said contact terminals, either an opening position for which said contact terminals are electrically isolated from one another, or a closure position for which said moveable member ensures electrical continuity between said contact terminals; and
a controlled device for actuating said moveable member between its two positions, said actuation device comprising a first control input for an electrical opening command and a second control input for an electrical closure command, this contactor being noteworthy in +that it incorporates, linked to said second control input for the electrical closure command, a prevention device able to prevent said moveable member from taking its closure position if the contact terminals of said contactor are simultaneously energized.
Advantageously, the electrical contactor of the invention can be such that its prevention device comprises:
two voltage detectors, respectively linked to said contact terminals of the contactor; and
a logic device, disposed between said voltage detectors and said second control input of the actuation device and able to prevent the closure of said contactor if said contact terminals are simultaneously energized.
Preferably, said logic device can comprise:
a first logic gate of NAND type, whose inputs are respectively linked to said voltage detectors; and
a second logic gate of AND type, of which an input is linked to the output of said first logic gate and of which the output is linked to said second closure control input of said actuation device, the other input of said second logic gate receiving said electrical closure command.